Hm, I'm going to say that it's different with everyone! After not progressing with my first labor I was given Pitocin... and labor contractions on that were extremely painful and one on top of the other. When I went naturally the second time, it was a walk in the park in comparison - just a longer, stronger version of braxton-hicks. When they started ramping up I'd say they were like strong period cramps that came in waves.

Mine just felt like menstrual cramps. Transition contractions were like bad menstrual cramps that came super close together without much break inbetween, but I wouldn't describe them as painful. Intense though. And then I didn't have contractions with pushing. Pushing felt like I was vommiting from my crotch.